Graham Douglas K, Salzberg Dana B, Kurtzberg Joanne, Sather Susan, Matsushima Glenn K, Keating Amy K, Liang Xiayuan, Lovell Mark A, Williams Sara A, Dawson Thomas L, Schell Michael J, Anwar Adil A, Snodgrass H Ralph, Earp H Shelton
Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado, USA.
Clin Cancer Res. 2006 May 1;12(9):2662-9. doi: 10.1158/1078-0432.CCR-05-2208.
The Mer receptor tyrosine kinase, cloned from a B-lymphoblastoid library, is the mammalian orthologue of the chicken retroviral oncogene v-eyk and sends antiapoptotic and transforming signals when activated. To determine if Mer expression is ectopic in T-cell acute lymphoblastic leukemia (ALL) and potentially important in leukemogenesis, we analyzed Mer expression in normal human thymocytes and lymphocytes and in pediatric ALL patient samples.
Reverse transcription-PCR, flow cytometry, and immunohistochemistry were used to determine expression of Mer in sorted human thymocyte populations, lymphocytes, and lymphocytes activated by phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. Mer expression in 34 T-cell ALL (T-ALL) patient samples was evaluated by reverse transcription-PCR, and Mer protein expression in a separate cohort of 16 patient samples was assayed by flow cytometry and Western blot.
Mer expression was absent in normal thymocytes or lymphocytes, and in T cells activated with phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. In contrast, Jurkat cells and T-ALL patient samples expressed unique 180 to 185 kDa Mer protein glycoforms. Substantial Mer RNA levels were principally observed in a subset of T-ALL patient samples that expressed B220 (P = 0.004) but lacked surface expression of CD3 (P = 0.02) and CD4 (P = 0.006), a phenotypic profile consistent with immature lymphoblasts. In addition, 8 of 16 T-ALL patient samples had Mer protein detected by flow cytometry and Western blot.
Transforming Mer signals may contribute to T-cell leukemogenesis, and abnormal Mer expression may be a novel therapeutic target in pediatric ALL therapy.
从B淋巴细胞样文库中克隆的Mer受体酪氨酸激酶是鸡逆转录病毒癌基因v-eyk的哺乳动物同源物，激活时可发出抗凋亡和转化信号。为了确定Mer在T细胞急性淋巴细胞白血病（ALL）中的表达是否异位以及在白血病发生中是否具有潜在重要性，我们分析了Mer在正常人胸腺细胞、淋巴细胞以及儿科ALL患者样本中的表达。
采用逆转录聚合酶链反应（RT-PCR）、流式细胞术和免疫组织化学来确定Mer在分选的人胸腺细胞群体、淋巴细胞以及由植物血凝素或佛波酯12-肉豆蔻酸酯13-乙酸盐/离子载体激活的淋巴细胞中的表达。通过RT-PCR评估34例T细胞ALL（T-ALL）患者样本中的Mer表达，并通过流式细胞术和蛋白质免疫印迹法检测另一组16例患者样本中的Mer蛋白表达。
正常胸腺细胞或淋巴细胞以及用植物血凝素或佛波酯12-肉豆蔻酸酯13-乙酸盐/离子载体激活的T细胞中均未检测到Mer表达。相比之下，Jurkat细胞和T-ALL患者样本表达独特的180至185 kDa Mer蛋白糖型。在一部分表达B220（P = 0.004）但缺乏CD3（P = 0.02）和CD4（P = 0.006）表面表达的T-ALL患者样本中主要观察到大量的Mer RNA水平，这种表型特征与未成熟淋巴母细胞一致。此外，16例T-ALL患者样本中有8例通过流式细胞术和蛋白质免疫印迹法检测到Mer蛋白。
转化的Mer信号可能有助于T细胞白血病的发生，异常的Mer表达可能是儿科ALL治疗中的一个新的治疗靶点。
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